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August 2006

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From:
R Sedlak <[log in to unmask]>
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TechNet E-Mail Forum <[log in to unmask]>, R Sedlak <[log in to unmask]>
Date:
Thu, 24 Aug 2006 17:02:23 -0700
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The definition of what is "the best cleaner" is the big variable here...

Water is great for cleaning charged, or polar, materials, like salts, and especially metal salts... these are the kinds of things I would be worried about if I were making/using boards...

No, water is not real good for cleaning uncharged, non-polar stuff, like organics, etc, but frankly this kind of stuff is not particularly dangerous to the performance of a board, so given a choice, I prefer to remove the bad guys, and leave the stuff that has little chance of hurting my board... (It is clear and obvious, I am not trying to get some purchaser to accept a lot of greasy boards...!)

As we say in chemistry, "Like dissolves like", and items like metal salts do not dissolve readily in organic solvents... so I will prefer water based systems, or preferably water based "saponifiers"... to vapor degreasers...  Water is not perfect, but nothing is, and what this leaves behind is preferable to what organic solvents leave behind.

Rudy Sedlak
RD Chemical Company

Edward Mines <[log in to unmask]> wrote: I have to disagree with the assertion that water is the best solvent for cleaning PC boards.

  It may be good for many (or even most no clean fluxes) but water alone will not touch various greases and oils including finger prints. Have you ever tried to clean you hands
  with water alone after changing the oil in your car?

  I don't know the legal consequences of using traditional vapor cleaning equipment or the current availability of effective vapor cleaning solvents, but I do know that vapor cleaning with trichlor was very effective when it was the industry standard. Other solvents will work too.

  It is important to remove all oily residues (finger prints, mold release agents etc) from PC boards prior to conformal coating - otherwise incomplete coverage can take place.
  Both MIL-I-46058 & IPC-CC-830 state that conformal coatings should be free from voids, skips and other breaks in the coating.

  Ed Mines


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